1. Field of the Invention
The invention is directed to a passive safety system that may be associated with an injection pen needle to protect a patient and/or healthcare professional using the pen needle from accidental needle sticks. The pen needle according to the invention provides for the non-injection end of a needle in a pen needle to be retracted into the device for safety.
2. Description of the Related Art
Accidental needlestick injuries from contaminated needles expose healthcare workers to the risk of infection from blood-borne pathogens, including the viruses that cause hepatitis B and C, and HIV. According to the Centers for Disease Control and Prevention, healthcare workers in the United States experience an estimated 600,000 exposures to blood each year, with RNs sustaining an overwhelming majority of these incidents.
While the injection device of choice in the U.S. remains the syringe, the demand for pen needles is growing rapidly. The use of self-injection pen needle devices is increasing due to the relative convenience, portability, and ease of use of these devices as compared to single use syringes. Pen needles are also becoming more commonplace in the hospital/clinical setting because certain drugs, such as human growth hormone and osteoporosis medications, are available only in pen needle form.
Healthcare workers have sustained needlestick injuries while removing pen needles from injection devices and subsequently disposing of them after administering an injection to patients. The needles are typically removed after each injection to minimize contamination of the medication in the cartridge and to prevent needle re-use. Removal of the needle generally requires the re-shielding of the injection end (also referred to herein as the “patient end”) of the needle using the outer protective cover in which it was supplied. Injuries from the patient end of the needle commonly occur at this time, but they can also occur during the removal of the pen needle from the pen as a result of the exposed non-patient end of the needle. To wholly address the problem of needle stick injuries, it would be desirable to have pen needles with safety features on both ends of the needle.
U.S. Pat. No. 6,986,760 B2, assigned to the assignee of the present application, teaches a pen needle and safety shield system wherein a safety shield, which normally encloses the needle cannula prior to use, permits retraction of the safety shield during injection and automatically extends and locks the shield in the extended enclosed position following use. The pen needle also prevents retraction of the shield during assembly of the shield and needle cannula and hub assembly on the pen injector.
U.S. Pat. No. 6,855,129 B2 discloses a safety needle assembly having a cylindrical housing with a needle mounted thereon for mounting onto a medical injection device. A shield is telescopically movable relative to the housing between a distal position, in which the shield covers the end of the needle, and a proximal position, in which the needle is exposed. A spring located inside the housing urges the shield in the distal direction. A locking element on the device is provided inside the housing with outwardly pointing locking protrusions. The locking element is a separate part provided between the spring and the shield and it is longitudinally moved simultaneously with the shield relative to the housing during use, so that the protrusions on the locking element are guided from a first position where the shield is in the distal position, to a second position where the shield is in the proximal position, to a third position where the locking protrusions are blocked by a blocking surface provided on the inside surface of the housing, so that further movement of the shield is irreversibly immobilized.
In contrast to the prior art, where the needle is fixedly mounted in a hub, in the present invention, the needle is movable with respect to the hub and may thus be retracted to a safe position within the hub after an injection is administered. Thus, the present invention addresses the need for a safety mechanism on the non-patient end of the needle.